One of the changes most frequently associated with aging is a loss of auditory sensitivity known as presbyacusis. Presbyacusis and its associated effects on auditory function often seriously reduce the ability of older adults to understand speech, which impacts everyday activities. The majority of research on presbyacusis has involved individual ear measures, ignoring the contribution of binaural and spatial hearing, although binaural interaction is known to be essential for effective communication and localization of speech and warning signals. Therefore, it is essential to quantify the type and the extent of the effects of presbyacusis on these abilities in order to achieve the long-term goal of developing effective remediation strategies for older adults. We intend to assess the speech understanding and sound localization skills of individuals with and without prebyacusis and to measure binaural detection on traditional detection tasks (e.g., MLD) and a spatial detection task. These detection tasks directly evaluate sensitivity to the predominant binaural cues of interaural time and intensity differences that are involved in the auditory processing of complex stimuli that occur in typical listening situations. The detection data will provide a direct means to systematically evaluate the theoretical relationships between speech understanding and basic sensitivity to interaural time and intensity cues described by Zurek (1993). The results of these experiments will also enable us to (1) identify binaural processing abilities of older individuals and (2) determine relationships between any impairment in basic binaural processing and performance on complex spatial tasks. Using this information we plan to design a simple binaural test or tests to predict the impact of presbyacusis on complex auditory signal processing and to develop effective management strategies to improve communication and facilitate auditory perception for older adults.